Chainsaw setting machine

ABSTRACT

A chainsaw sharpener mounted on and forward of the electric motor of a sharpener body ( 2 ) via a mounting portion ( 9 ) having a guide body ( 8 ) with an upper plate face ( 80 ) and wall faces ( 81   a  to  81   e ) which have a substantial X-shape as seen in plan view, and which are fit into and along an upper part of the saw chain in alignment with a sharpening angle of either a left or right cutter blade ( 31, 32 ) of a saw chain ( 30 ). Formed at a substantially central surface of the guide body ( 8 ) is an exposure portion made of openings ( 85, 86 ) which make it possible to watch, from above, the grinding tool ( 7 ) and a cutting edge of a cutter blade to be sharpened. A guide portion ( 87 ) presses, from above, the cutter blade to be sharpened so as to prevent the cutter blade from wobbling or tilting, and further to define an accurate cutting edge angle.

TECHNICAL FIELD

The present invention relates to a chainsaw sharpener in which a roundshaft-shaped grinding tool attached to an end of an electric motor isrotated to grind and thereby sharpen, at a side portion thereof, acutting edge of a cutter blade of a saw chain provided on a chainsaw. Itparticularly relates to a chainsaw sharpener which enables sharpening,aligned with an accurate sharpening angle and cutting edge angle, easilyin a short time with just a simple operation of fitting it from aboveinto the saw chain in an orientation corresponding to either a left orright cutter blade, and pushing it forward.

BACKGROUND ART

Conventionally, a chainsaw has attached thereto a saw chain having anendless shape. The saw chain has left-facing cutter blades andright-facing cutter blades provided at constant intervals and indirections opposite to each other. Upper blades of these blades have asharpening angle which is, for example, tilted backward at 30°. Cuttingedges of the upper blades have a cutting edge angle of, for example,60°.

These sharpening angle and cutting edge angle are required for cuttinge.g. a wood. If a cutting edge is chipped or worn, it becomes dull. Thismay cause extra time required to cut a wood, and provide extra load on aworker, and further prevent the saw chain from biting into the woodsufficiently at the time of starting cutting the wood, which may bringabout a dangerous situation of kickback (backlash).

For this reason, it is necessary to grind so that the cutting edgebecomes sharp. In the following description, sharpening means grindingof a cutting edge aligned with the sharpening angle and the cutting edgeangle.

Conventionally, this sharpening has been done by manual work using e.g.a round shaft file. However, the sharpening by manual work is low inefficiency, and in particular requires expertise to align a file with anaccurate sharpening angle and cutting edge angle. If the sharpeningangle or the cutting edge angle is not accurate when cutting a thicktree, it may not be possible to cut it straight, or it may cause a dullcutting edge. A technology to hold a file in alignment with an accuratesharpening angle or cutting edge angle is known from e.g. JapanesePatent Publication Sho 44-29030 which discloses a sharpening process fora chainsaw. This sharpening process uses a method of fixing a holder forholding a file to a saw plate using a thumbscrew. Thus, this requireslaborious work of loosening and tightening the thumbscrew every timewhen sharpening each cutter blade.

Recently, instead of sharpening by manual work, a sharpener with a handytype electric motor is more often used.

Known examples of this kind of sharpeners are e.g. an upper bladegrinder for a chainsaw as described in Japanese Laid-open PatentPublication Sho 61-24121, and a chainsaw sharpener not requiring agrinding tool as described in Japanese Laid-open Utility ModelPublication Sho 57-186227.

DISCLOSURE OF INVENTION

However, the grinder described in Patent Document 2 (sic JapaneseLaid-open Patent Publication Sho 61-24121) and the sharpener describedin Utility Model Document 3 (sic Japanese Laid-open Utility ModelPublication Sho 57-186227) are used in a manner that a holder or a motoris held by a hand, while a cover plate or an angle adjustment plate isplaced on a saw chain. It is understood that mere placing of the coverplate or the angle adjustment plate on the saw chain is not sufficientto stabilize the posture of the grinder or the sharpener, and that ahand is likely to wobble during the sharpening work, and thus that it isnot easy to continue the sharpening work in alignment with an accuratesharpening angle or cutting edge angle. An attempt to align with acorrect sharpening angle or cutting edge angle is likely to tire thehand gradually and thereby produce sharpening with a bad finish.

In view of this, the present inventor has diligently attempted a studyof a construction of an ideal sharpener that is high in work efficiency,and easily and accurately enables orienting and positioning of thesharpening angle and the cutting edge angle, and that can do sharpeningof (sic against) e.g. wobbling or tilting of a cutter blade during thesharpening work.

It is an object of the present invention to provide a sharpener thatmakes it possible, as a matter of course, to do sharpening in highefficiency by contacting, with a cutting edge, a grinding tool (roundshaft file) rotated by an electric motor at a high speed, and that makesit possible to obtain an accurate sharpening angle and cutting edgeangle with almost just one-touch operation of fitting a guide body intoa saw chain in an orientation corresponding to a left or right cutterblade, and pushing forward its wall faces which are directed downward,and moreover that can prevent the cutter blade to be sharpened from e.g.wobbling or tilting.

To achieve the above object, the present invention provides a chainsawsharpener with a round shaft-shaped grinding tool attached to an end ofa drive shaft of a handy type electric motor, wherein mounted on andforward of the electric motor of a sharpener body via a mounting portionis a guide body having, formed therein, an upper plate face and wallfaces which have a substantial X-shape as seen in plan view, extendingin two directions, and which are fit into and along an upper part of thesaw chain in alignment with a sharpening angle of either a left or rightcutter blade of the saw chain, wherein formed at a substantially centralsurface of the guide body is an exposure portion made of an opening or acurved portion or both of these which make it possible to watch, fromabove, the grinding tool and at least a cutting edge of a cutter bladeto be sharpened, and wherein provided on inside or side of the exposureportion is a guide portion for pressing, from above, the cutter blade tobe sharpened so as to prevent the cutter blade from wobbling or tilting,and further to define an accurate cutting edge angle.

In a sharpening work using the sharpener of the present invention, aside of the grinding tool rotating at a high speed is brought intocontact with the cutting edge of a cutter blade for grinding, with theupper plate face of the guide body being placed on an upper part of thesaw chain, and with the wall faces on the near side being pressedagainst a guide bar (saw plate) of the chainsaw. In a saw chain, cutterblades are provided at constant intervals to face alternately left andright. Accordingly, it is necessary to change the orientation of thegrinding tool depending on the sharpening of the left or right cutterblades. In the sharpener of the present invention, the guide body has anX-shape as seen in plan view according to the different orientations ofthe grinding tool, so that an accurate sharpening angle and cuttingangle can be obtained by fitting the guide body into the saw chain fromabove in alignment with either of the two directions of the X-shape, andpushing it forward.

Specifically, a grinding tool is not always oriented at an accuratesharpening angle by merely fitting and placing a guide body into and ona saw chain from above, because the guide body is designed with anallowance for the front-to-back width of the guide body relative to theleft-to-right width of the saw chain so as to make it easy to fit theguide body into the saw chain from above. So, a design has been madethat sets the two directions of the X-shape, as seen in plan view, to bedirections in which the grinding tool is aligned with the sharpeningangle, whereby an accurate sharpening angle and cutting edge angle canbe obtained by fitting the guide body into the saw chain from above inan orientation of either direction of the X-shape in alignment with theorientation of a left or right cutter blade, and by pushing it forward.For this reason, wall faces, which are directed downward and are to bepressed against the guide bar (saw plate) for alignment with an accuratesharpening angle, are formed at a near side edge of the guide bodycorresponding to the X-shape as seen in plan view. By pushing the wallfaces forward, the guide body is prevented from wobbling.

Note that in many kinds of chainsaws, a saw chain has a shape such thatits central part slightly expands in an up-down direction. Thus, with anexposure portion, made of an opening or a curved portion to make itpossible to watch a cutter blade to be sharpened and the grinding toolfrom above, being formed at a substantially central location in an uppersurface of the guide body, it is not possible to prevent a cutter bladefrom wobbling or tilting due to its contact with the grinding toolrotating at a high speed. However, in the guide body of the sharpener ofthe present invention, a guide portion for pressing, from above, thecutter blade to be sharpened is provided on inside or side of theexposure portion so as to prevent the cutter blade from wobbling ortilting.

Further, this guide portion also has a big role to press, from above, acutter blade to be sharpened so as to enable grinding which is alignedwith a cutting edge angle of the cutter blade. In other words, thepositional relationship between the guide portion and the grinding toolis defined to obtain an accurate cutting edge angle. Furthermore, thisguide portion has a role, as well, to protect the face of a worker frommetal power and sparks produced in the sharpening work.

The sharpener of the present invention has a structure as describedabove, so that it enables alignment with an accurate sharpening angleand cutting edge angle, with just an operation of fitting it from aboveinto the saw chain in alignment with a central position of a cutterblade to be sharpened, and pushing it forward. So, even a personinexperienced in the sharpening can easily do an accurate sharpening ina short time. In this sharpener, an electric motor is used which uses ahome power supply of 100V AC or uses a rechargeable battery. As anexample of a preferable grinding tool, a diamond grindstone can be givenwhich is formed of a round shaft having diamond particles fixed on anouter peripheral surface except a rear portion thereof.

The chainsaw sharpener according to the present invention enablessharpening in high efficiency, using a handy type electric motor. Inparticular, since the guide body has an X-shape to be able to fit intoand in alignment with the sharpening angle of the left or right cuttingedge of the saw chain, an accurate sharpening angle can be obtained withalmost just one-touch operation of fitting the guide body into an upperpart of the saw chain in alignment with a direction which is alignedwith an orientation of a cutter blade to be sharpened, and pressing itagainst the guide bar of the chainsaw.

Furthermore, as a result of providing, on the upper plate face of theguide body, the guide portion to define an accurate cutting edge angleby pressing, from above, a cutter blade to be sharpened, it has becomepossible to prevent the cutter blade from wobbling or tilting and to dosharpening aligned with an accurate cutting edge angle, even when thegrinding tool rotating at a high speed is brought into contact with thecutter blade to be sharpened. As a result of the above, it is possibleeven for a man or a woman, inexperienced in the sharpening, to do anaccurate sharpening in a short time, making it unnecessary, as well, topatiently continue using a chainsaw which has become dull.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a chainsaw sharpener according toan embodiment of the present invention;

FIG. 2 is a perspective view of the sharpener as seen from diagonallybelow;

FIG. 3 is a plan view showing a main part of the sharpener;

FIG. 4 is its rear view;

FIG. 5 is its right side view;

FIG. 6 is its cross-sectional side view as seen from right;

FIG. 7A is a plan view showing a state of sharpening a cutter bladepositioned on the left side of a saw chain (on the near side as seenfrom a sharpening worker), and similarly FIG. 7B is its partiallyenlarged view;

FIG. 8 is a cross-sectional side view showing a state of sharpening acutting edge of a cutter blade on the left side;

FIG. 9 is similarly a cross-sectional front view showing a state inwhich a cutting edge angle is defined by a grinding tool and a guideportion;

FIG. 10A is a front view showing a state of sharpening a cutter blade onthe right side of the saw chain, and FIG. 10B is its partially enlargedview;

FIG. 11 is a cross-sectional side view showing a state of sharpening acutter blade on the right side; and

FIG. 12 is a cross-sectional front view showing a state in which acutting edge angle is defined by the grinding tool and a guide portion.

BEST MODE FOR CARRYING OUT THE INVENTION

A best mode for carrying out the present invention will be describedhereinafter with reference to the drawings.

FIG. 1 to FIG. 6 show a chainsaw sharpener according to an embodiment ofthe present invention. As shown in these drawings, a chainsaw sharpener1 according to the embodiment of the present invention is formed in amanner that a guide body 8 is detachably mounted on and forward of asharpener body 2 which has a round shaft-shaped grinding tool 7 mountedon a front end portion of a drive shaft of an electric motor 3.

The electric motor 3 is a handy type to be driven by a DC power supplyor an AC power supply, which is taken from outside, or a rechargeablebattery. FIG. 1 and FIG. 2 show an electric motor 3 to be driven by ahome power supply. The electric motor 3 used has a body case with apower supply switch 4 to be slided to turn the power supply on and off,and with a brake button 5 to brake the rotation of the drive shaft, andfurther has a power supply cord 10 extending from a rear end thereof fortaking a power supply from outside.

A front part of the body case of the electric motor 3 has a narrowershape, and has a front end formed of a cylinder-shaped mounting portion3 a having a screw groove cut on an outer peripheral surface thereof formounting the guide body 8. Using a chuck 6 mounted on the front endportion of the drive shaft of the electric motor 3, the grinding tool 7formed of a round shaft having diamond grindstone fixed thereto ismounted, thereby forming the sharpener body 2.

As shown in FIG. 1 to FIG. 6, the guide body 8 has an upper plate face80 having a substantial X-shape as seen in plan view. Using screws 11,11, a mounting member 9 formed of a big nut is attached to mountingplate portions 88 a, 88 b which are formed at a center back part of, andtilted diagonally downward from left and right of, the upper plate face80. The mounting member 9 is screwed onto the mounting portion of thefront end of the electric motor 2 (sic 3) so that the electric motorbody 2 (sic 3) and the guide body 8 are integrally assembled.

Further, each of branch faces 80 a, 80 b, 80 c, 80 d which form theupper plate face 80 of the guide body 8 is formed to be wider than thewidth of a saw chain 8 (sic) to some extent. For example, according to aprototype guide body 8 which the inventor has made, each of the branchfaces 80 a, 80 b, 80 c, 80 d has a width of about 16 mm.

A rib 82 bent downward is formed at a position along a front edge of thetwo branch faces 80 a, 80 b which are directed diagonally forward.According to the prototype guide body 8 which the inventor has made, therib 82 has a height of about 9 mm for example.

Further, a rib 83 b bent downward is formed at a position along a rightside edge of the branch faces 80 b, 80 c which are directed diagonallyright forward and diagonally right backward as seen from the electricmotor 3. Similarly, a rib 83 a bent downward is formed at a positionalong a left side edge of the branch faces 80 a, 80 d, as well, whichare directed diagonally left forward and diagonally left backward.According to the prototype guide body 8 which the inventor has made,these ribs 83 b, 83 a have a height of about 5 mm for example. The frontedge and the left and right side edges as well as these ribs 82, 83 b,83 a have an arc shape.

Furthermore, pressure plate faces 81 a, 81 b, 81 d, 81 c which serve aswall faces for pressing against a guide bar (saw plate) of the chainsaw,and which are directed downward, are formed on front end faces of theribs 83 a, 83 b and on back end edges of the left and right branch faces80 d, 80 c which are directed backward of the left and right branchfaces 80 b, 80 a that are directed diagonally forward. Portions of thesepressure plate faces 81 a, 81 b, 81 d, 81 c directed downward to partwayfor about two-thirds of the width of the respective branch faces 80 a,80 b, 80 c, 80 d are directed forward, and are then directed downward.According to the prototype guide body 8 which the inventor has made,these pressure plate faces 81 a, 81 b, 81 d, 81 c have a height of about27 mm.

Formed at a center in the left-to-right direction in the upper plateface is an exposure portion made of an opening 85 of a size which makesit possible for a sharpening worker, when sharpening, to watch thegrinding tool 7 and a cutting edge of a cutter blade (not shown).Further, an exposure portion made of an opening 86 is also formed nearand right of the opening 85. At a narrow portion of the upper plate facepositioned between the both openings 85, 86 and extending in thefront-to-back direction, a guide portion 87 is formed which is to press,from above, the cutter blade to be sharpened so as to prevent the cutterblade from wobbling or tilting due to contact between the grinding tool7 rotating at a high speed and the cutter blade, and which is to definean accurate cutting edge angle. The guide portion 87 serves as a markerto align a side edge of the grinding tool 7 with the cutting edge of thecutter blade, and further serves to prevent metal powder produced bygrinding from flying upward.

Next, referring to FIG. 7 to FIG. 12, a method of using the chainsawsharpener 1 according to the embodiment of the present invention will bedescribed.

As shown in FIG. 7A, FIG. 7B and FIG. 8, when sharpening a cutter blade31 positioned on the left side of the saw chain (on the near side of, asseen from, the sharpening worker), align it with A-A direction of theguide body 8 and the orientation of the saw chain 30, and fit and placeit into and on the saw chain 30 from under or beneath the openings 85,86 formed at a center in the upper plate face 80.

Align the position of the grinding tool 7 with a cutting edge 31 b of anupper blade 31 a of the cutter blade 31 on the left side, and thereafterpush the entire sharpener 1 forward. Thereby, the horizontal posture ofthe grinding tool 7 is secured, and the sharpening angle can beaccurately defined. Furthermore, as shown in FIG. 9, the upper blade 31a of the cutter blade 31 to be sharpened is pressed from above by theguide portion 87. Accordingly, the cutter blade 31 is prevented fromwobbling or tilting even if the grinding tool 7 rotating at a high speedis brought into contact with the cutter blade 31.

Thus, an accurate cutting edge angle along the cutting edge 31 b isaccurately defined on the basis of the positional relationship betweenthe guide portion 87 and the grinding tool 7. In this state, the cutterblade 31 on the left side is sharpened.

On the other hand, as shown in FIG. 10A, FIG. 10B and FIG. 11, whensharpening a cutter blade 32 positioned on the right side of the sawchain (on the far side of, as seen from, the sharpening worker), fit andplace the branch faces 80 d, 80 b of the upper face 80 of the guide body8 into and on the saw chain 30 from above the saw chain 30 in alignmentwith B-B direction of the guide body 8 and the orientation of the sawchain 30.

Align the position of the grinding tool 7 with a cutting edge 32 b of anupper blade 32 a of the cutter blade 32 on the right side, andthereafter push the entire sharpener 1 forward. Thereby, the horizontalposture of the grinding tool 7 is secured, and the sharpening angle canbe accurately defined. Furthermore, as shown in FIG. 12, the upper blade32 a of the cutter blade 32 to be sharpened is pressed from above by theguide portion 87. Accordingly, the cutter blade 32 is prevented fromwobbling or tilting even if the grinding tool 7 rotating at a high speedis brought into contact with the cutter blade 32.

Thus, an accurate cutting edge angle along the cutting edge 31 b (sic 32b) is accurately defined on the basis of the positional relationshipbetween the guide portion 87 and the grinding tool 7. In this state, thecutter blade 32 on the right side is sharpened.

Note that for sharpening the left and right cutter blades 31, 32 usingthe sharpener 1, it is possible to alternately sharpen the left andright cutter blades 31, 32. It is also possible to first sharpen all thecutter blades 31 on the left side (or cutter blades 32 on the rightside), and thereafter sharpen all the cutter blades 32 on the right side(or cutter blades 31 on the left side).

INDUSTRIAL APPLICABILITY

The chainsaw sharpener of the present invention is to sharpen thecutting edge of a saw chain provided in a chainsaw by grinding orabrading. It is small in size and easy to use, and enables sharpening ofa cutter blade, aligned with an accurate sharpening angle and cuttingedge angle, by just aligning the orientation of an electric motor, heldby a single hand, with a horizontal direction on either left or right,and pushing it forward. Thus, even a user having no experience insharpening a saw chain can do the sharpening well. Further, since it hasa simple construction, and a construction unlikely to cause failure, itcan be offered to consumers at a low price, so that not only new demand,but also replacement of conventional products can be expected.

1. A chainsaw sharpener for a saw chain with a round shaft-shapedgrinding tool (7) which is attached to an end of a drive shaft of anelectric motor (3), and which receives rotation force of the electricmotor (3) so as to rotate, wherein a guide body (8) is securely fastenedon and forward of the electric motor (3) of a sharpener body (2) via amounting plate portion 88 a, 88 b so that the electric motor (3) and theguide body (8) are integrally assembled; where said guide body having,formed therein, an upper plate face (80), comprising four branch faces80 a, 80 b, 80 c and 80 d that are wider than a saw chain and which havea substantial X-shape as seen in plan view, extending in two directions,and which are fit into and along an upper part of the saw chain (30) inalignment with a sharpening angle of either a left or right cutter blade(31) of the saw chain (30); ribs 83 a and 83 b that are bent downwardand are formed at positions along a right side edge and a left side edgerespectfully of branch faces 80 a, 80 d and 80 b, 80 c; and wallpressure plate faces (81 a, 81 c, 81 d, 81 b) that are directed downwardand that are formed on a front end faces of said ribs 83 a and 83 b andon back end edges of the left and right branch faces 80 d, 80 c andserve as wall faces for pressing against a guide bar of the chainsawsuch that manually pushing said electric motor toward said guide bar(40) of the chainsaw causes either wall pressure plate faces (81 a, 81c) or (81 b, 81 d) to press against said guide bar (40) therebyaccurately aligning said grinding tool with the sharpening angle andpreventing wobbling; wherein formed at a substantially central surfaceof the guide body (8) is an exposure portion made of an opening or acurved portion or both of these which make it possible to watch, fromabove, the grinding tool (7) and at least a cutting edge (31 b, 32 b) ofa cutter blade (31, 32) to be sharpened, and wherein provided on insideor side of the exposure portion is a guide portion (87), which is anarrow portion of the upper plate face (80) extending in a front-to-backdirection, so that when said guide portion (87) is pressed from abovesaid guide portion (87) contacts and secures an upper blade (31 a) ofsaid cutter blade (31) to prevent wobbling or tilting, and to further todefine an accurate cutting edge angle.